1. Technical Field
The present invention relates to a pair of shutter glasses and an image display system.
2. Related Art
There has been a known image display system (3D display apparatus) including an image display apparatus that displays images and a pair of shutter glasses worn by a viewer and allowing the viewer to stereoscopically view the images displayed by the image display apparatus through the shutter glasses (see JP-A-2010-117437, for example).
FIGS. 12A and 12B describe the operation of an image display system of related art.
Specifically, FIG. 12A is a timing chart showing the timing at which image data are written along each scan line in an image display apparatus, and the vertical axis of FIG. 12A corresponds to the vertical direction of the image display apparatus (the vertical axis represents the positions of the uppermost scan line L1 to the lowermost scan line Ln). FIG. 12B is a timing chart showing the timings at which a shutter for the left eye (lower part of FIG. 12B) and a shutter for the right eye (upper part of FIG. 12B) that form shutter glasses switch their states between a light transmitting state OP and a light blocking state CL.
In FIG. 12A, to diagrammatically show the timings at which image data are written along the scan lines L1 to Ln, a straight line is drawn to connect a write start timing (update start timing) Ws, at which writing image data along the scan line L1 starts, to a write end timing (update end timing) We, at which writing image data along the scan line Ln ends. It is noted that images displayed by the image display apparatus are labeled with characters for ease of description as follows: An image for the left eye is labeled with “L” and an image for the right eye is labeled with “R” (a parallelogram area represents one of the images described above).
The image display apparatus described in JP-A-2010-117437 is formed of an LCD display including a liquid crystal panel that displays an image in a line sequential drive scheme. The LCD display writes image data sequentially from the uppermost scan line L1 to the lowermost scan line Ln in a vertical scan period, each of Tv1 to Tv4, which is triggered by a vertical sync signal, to update a displayed image, as shown in FIG. 12A. The LCD display updates the displayed image in a first period T1 (vertical scan periods Tv1 and Tv2) and a second period T2 (vertical scan periods Tv3 and Tv4), which are alternately switched therebetween. Specifically, the displayed image is updated to an image for the left eye twice in the first period T1 and updated to an image for the right eye twice in the second period T2.
Each of the shutter glasses (shutter for left eye and shutter for right eye) described in JP-A-2010-117437 is formed of what is called a liquid crystal shutter.
The state of the shutter for the left eye becomes the light transmitting state OP, in which substantially the entire amount of light is transmitted, only in the period from the second left-eye image update start timing Ws to the following first right-eye image update start timing We (vertical scan period Tv2) in a first period T1, whereas becoming the light blocking state CL, in which substantially the entire amount of light is blocked, in the other periods, as shown in the lower portion of FIG. 12B.
On the other hand, the state of the shutter for the right eye becomes the light transmitting state OP only in the period from the second right-eye image update start timing Ws to the following first left-eye image update start timing Ws (vertical scan period Tv4) in a second period T2, whereas becoming the light blocking state CL in the other periods, as shown in the upper portion of FIG. 12B.
That is, the state of each of the shutters for the left and right eyes becomes the light transmitting state OP except periods during which images for the left and right eyes are mixed with each other (a period during which an image for the left eye is updated to an image for the right eye or a period during which an image for the right eye is updated to an image for the left eye). The viewer therefore visually recognizes only an image for the left eye with the left eye and only an image for the right eye with the right eye. The viewer therefore stereoscopically views the displayed images with the aid of parallax.
In the image display system described in JP-A-2010-117437, however, since the state of each of the shutter glasses becomes the light transmitting state OP only in the period described above, the period during which the viewer can visually recognize an image for the left or right eye disadvantageously shortens, resulting in decrease in brightness of displayed images to be visually recognized.